Methods of Study in Natural History.

Darwin and Humboldt: Their Lives and Work

Darwin and Humboldt: Their Lives and Work

Principles of Zoology: Races of Animals, Living and Extinct

Principles of Zoology: Races of Animals, Living and Extinct

Principles of Zoölogy

Principles of Zoölogy

Essay on Classification

Essay on Classification

Principles of Zoology: Touching the Structure, Development, Distribution, and Natural Arrangement of the Races of Animals, Living and Extinct: With Numerous Illustrations: Part I, Comparative Physiology: For the Use of Schools and Colleges